Potential of Flame Ionization Detection Coupled On-Line with Microcolumn Liquid Chromatography Using Aqueous Eluents and an Eluent-Jet Interface

Abstract

The potential of the on-line coupling of microcolumn liquid chromatography (μLC) using aqueous eluents with a flame ionization detector (FID) was evaluated. An eluent-jet interface was modified to allow the efficient introduction of the eluent into the FID. The potential of the method is demonstrated by the μLC–FID determination of lower alcohols and bis(2-hydroxyethylthio)alkanes on porous and non-porous stationary phases, respectively. Flow injection analysis (FIA)–FID experiments with highly polar, thermolabile, semi-volatile and non-volatile compounds like amino acids, organic acids, alkylphosphonic acids, and carbohydrates showed the developed configuration to be a promising approach for the detection of a wide range of analytes. Compared with a nebulization interface, the eluent-jet interface showed 4–10 times higher peaks for citric acid. Detection limits by FIA for all compounds were in the range of 0.2–5 ng injected. With ribose as test compound, plots of peak height vs. amount injected showed good linearity (r2 > 0.999) in the range of 75–12,000 μg/mL. The repeatability showed relative standard deviations of less than 5%.